Tico CNG Chassis
Electronic Control Unit (ECU)
Removal, Replacement and Isolation
ENP-723
May 30, 2019
Copyright ©2019. Agility Fuel Solutions. All Rights Reserved.

1. Introduction
The Agility service team has identified a potential issue related to the fuel system driveaway
protection circuit on Tico compressed natural gas (CNG) tractors. Frequent starter
engagements and exposure to high current in the starter circuit may cause the electronic
control unit (ECU) to prematurely fail. ECU failure will lead to a no crank/no start condition.
Agility has designed a wiring harness to remedy this condition. As a precautionary measure
Agility is also supplying a replacement ECU. After performing the repair, return the ECU with
the supplied Repair Report Form using provided return merchandise authorization (RMA)
label.

1

Figure 1.
Fuel Management Module (FMM) (1) location on Tico CNG chassis.

1.1 Warning Messages Used in this Bulletin
.

⚠ CAUTION.

Damage to equipment, engine, fuel system or vehicle is possible if instructions are not
followed.
.

NOTICE .

Best practices or hints to help an operation or procedure go smoothly.

2. Affected Units
Tico CNG tractors.

ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

2 of 9

3. Tools and Materials
Description
Long Phillips screwdriver

7/16-in. socket wrench

10 mm wrench

9/16-in. socket wrench

Side cutters

Zip ties

Agility Fuel Solutions p/n 69500003 kit contents (Figure 2):
Qty: 1 - ECU, p/n 20101205
Qty: 1 - Relay harness, p/n 10400870
Qty: 1 – TICO CNG ECU Report form ENP-038, p/n 69500004

2

4
3

Figure 2.
Agility Fuel Solutions kit p/n 69500003 contents:
ECU (not visible), relay harness (2), report form ENF-038, (3), RMA label (4).
NOTE: If multiple repairs are required at a single facility the Agility package will contain
a corresponding number of repair kits with a single RMA label (4). Figure 2

4. Corrective Action / Procedure
Remove and replace fuel system ECU and install replacement relay harness.

⚠ CAUTION.
Observe all safety measures for CNG vehicle repair including all facility requirements.

⚠ CAUTION.
▪ Park vehicle, set parking brake, remove ignition key, and secure vehicle tires with wheel
chocks.
▪ If equipped: Lock out/tag out battery disconnect.
1. Locate fuel management module (FMM) (1) on driver’s side frame rail. Figure 1
2. Remove 7/16-in. bolts (not shown) securing FMM bottom cover and remove FMM cover
to gain access to fuel system ECU.
3. Locate ECU (2) on upper right-hand corner of FMM. Figure 3
ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

3 of 9

2

Figure 3.
FMM with cover removed to reveal ECU (2) location.
4. The ECU (2) is a black controller with three ports: 4-pin harness connector (5), 16-pin
harness connector (6), 9-pin D-Sub connector (7) which should be capped. Figure 4
8

7

6

2

5

Figure 4.
Agility Fuel Solutions ECU (2), 4-pin harness connector (5), 16-pin harness connector (6),
data label (6), NOTE: D-sub connector port (7) should be capped.
5. Remove wire harness connectors (9 & 10) from ECU by pressing locking tab (11) on the
side of each connector housing while pulling connector downward. Figure 5
.

⚠ CAUTION. Always remove harnesses using the connector and not the wires.
2

9
11

10

12

Figure 5.
Large yellow arrows indicate 4-pin (9) and 16-pin (10) connectors.
Press each locking tab (11) while pulling on connector to remove harness from ECU (2).

⚠ CAUTION. Avoid contact with ECU connector ports.
ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

4 of 9

6. Using a long (~12-in.) Philips screwdriver and a 10mm wrench, remove ECU fasteners
(12) securing ECU (2) to the FMM. Figure 5
7. Gently remove ECU (2) taking care not to damage connector contacts. Figure 5
8. Use provided repair report form ENF-038 (4) (Figure 2) to record the serial number from
label (6) of both removed ECU and replacement ECU 20101205. Figure 4
.

NOTICE . ECU serial number begins with “CT-”.

9. Install replacement ECU 20101205 (not shown) by reversing Steps 5 through 7.
10. Use 9/16-in. socket to remove four bolts (not visible) retaining catwalk grate (13). Figure 6

13

Figure 6.
Remove four 9/16-in. bolts (not shown) from locations indicated below catwalk grate (13).
11. Remove catwalk grate (13). Figure 7
13

Figure 7.
Move catwalk grate (13) aside to access grounding studs.

ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

5 of 9

12. The relay harness (not shown) may be identified the part number, 10400870, on the label.
A relay (14) protects the ECU, while connector 12015792 (15) interfaces with the fuel
system harness, connector 12010973 (16) with the OEM harness, and a grounding ring
(17) connects to a bolt on the chassis ground plate. Figure 8
15

16
14

17

Figure 8.
Relay harness p/n 10400870 diagram: relay (14), fuel system harness connector 12015792
(15), OEM harness connector 12010973 (16), grounding ring (17).
13. Disconnect fuel system harness to OEM harness connectors at junction (18). Figure 9

18

Figure 9.
Inset with closeup of fuel system harness to OEM harness junction (18).
14. Connect relay harness 10400870 OEM connector (16) (two yellow wires) and fuel system
connector (15) (blue and purple wires) to respective OEM harness connector and fuel
system harness connectors. Figure 10

ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

6 of 9

16
15

Figure 10.
Relay harness 10400870 installed in serial between OEM harness and fuel system
harness.
15. Remove nut (22) from stud (20) on grounding plate at rear of cab and use it to secure
relay harness grounding ring terminal (17). Figure 11

22

20

19

21

Figure 11.
Correct relay harness ground wire installation: line (19) shows routing, ovals (21) zip tie
locations, grounding ring terminal stud (20) and nut (22).
ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

7 of 9

16. Loop excess grounding wire length onto itself inside of frame (19), secure to OEM harness
using zip ties at locations (21), and clip zip tie tag ends using side cutters. Figure 11
17. Route and secure relay harness to OEM harness using zip ties. Figure 12. Refer also to
“ENP-524: Natural Gas Fuel System Routing, Clipping and Installation Guide.”

23

Figure 12.
Secure relay harness, connector junctions and relay to vehicle harness with zip ties at
locations (23); use additional zip ties as needed.
18. Reinstall FMM bottom cover and confirm FMM door is closed.
19. If equipped: Remove lock out/tag out battery disconnect.
20. Verify proper vehicle operation.
21. Reinstall catwalk grate (13) using four bolts (not shown). Figure 6
22. Remove wheel chocks and return vehicle to service.
23. Update vehicle maintenance and repair records.
24. After completing the repair, please return the ECU following the steps below:
a. Return ECU(s) using the same shipping box Agility used for replacement kit(s).
b. Place ECU(s) along with completed ENF-038 report form(s) in the zip lock bag(s)
from the replacement kit(s). Figure 2
c. Pack ECU(s) carefully to prevent damage during transport.
d. Affix RMA label (4) to box. If multiple kits were sent to the facility, one label is
supplied to return all removed ECU(s). Figure 2
For reference, the correct shipping address is as follows:
Agility Fuel Solutions
ATTN: RMA Parts Return
10007 Elm Av
Fontana, CA 92335
e. Write “RMA E0168” on outside of box.

ENP-723: Tico CNG Chassis ECU Replacement and Isolation

(Downloaded Copy is Not Controlled)

8 of 9

5. Warranty Information
This procedure is covered under warranty. Standard repair time (SRT) is 0.8 hours. Please
refer to Warranty Manual, ENP-067, for warranty reimbursement procedures.
For parts and support, contact Agility Fuel Solutions Customer Care: +1 949 267 7745, toll
free: +1 855 500 2445 or [email protected]
Proprietary Statement
The information provided within this document is proprietary and confidential. All prior
versions, including updates and revisions forwarded separately, are proprietary. The
information provided by Agility Fuel Solutions to its customers and clients is solely for the use
of those customers and clients. No portion of this publication may be reproduced or
distributed without express written consent of Agility Fuel Solutions. Agility Fuel Solutions
reserves the right to utilize the intellectual property contained within this publication as
content for any other publication produced by Agility Fuel Solutions.
Trademark Notice
Agility® and TUFFSHELL® are registered trademarks of Agility Fuel Solutions. Drop-N-Go™
is a trademark of Agility Fuel Solutions. Trademarks of other manufacturers are the property
of their respective companies.
Agility Fuel Solutions | 3335 Susan Street Suite 100 | Costa Mesa, CA 92626 USA
www.agilityfuelsolutions.com

Revision
--

Description
Initial Release

ENP-723: Tico CNG Chassis ECU Replacement and Isolation

Author
C. Grasso

Approved By
Team

Date
05/30/2019

(Downloaded Copy is Not Controlled)

9 of 9